The present invention relates to an electric vehicle including a motor and an engine for driving the vehicle.
There is an electric vehicle including a motor and an engine for driving the vehicle (for example, refer to JP-A-8-98322, JP-UM-B-55-40806, JP-A-4-297330 and JP-A-2010-200426).
Electric vehicles including motors and engines for driving the vehicles (so-called hybrid cars) are roughly classified into a “one-motor parallel system” and a “two-motor series parallel system”. For development of a sports utility vehicle with high cross-country performance (hereinafter referred to as cross-country SUV), the “one-motor parallel system” is typically selected for the following reason. That is, when a cross-country SUV travels mainly using a motor, it is difficult to satisfy the performance of “continuous travel on a rough road” and “traction” required in the cross-country SUV due to the capability of the motor. A vehicle using the “two-motor series parallel system” is unsuitable for cross-country travel because the vehicle cannot travel using an engine alone. The “one-motor parallel system” is a system in which an engine is mainly used and its driving force is assisted by a motor. A vehicle using the “one-motor parallel system” can travel using the engine alone. It can be therefore said that the “one-motor parallel system” is suitable for cross-country travel.
In the configuration of an electric vehicle using the “one-motor parallel system”, which is, for example, an electric vehicle 50 shown in FIG. 2, a clutch 52 and a drive motor 53 are provided between an engine 51 and a transmission 54 so as to be connected to a rear wheel drive shaft 58 and rear wheels 59 through a transfer 55, a rear propeller shaft 56 and a rear differential 57 and also connected to a front wheel drive shaft 62 and front wheels 63 through the transfer 55, a front propeller shaft 60 and a front differential 61. Incidentally, the reference numerals 64, 65 and 66 in FIG. 2 represent an exhaust pipe, a fuel tank and a battery respectively.
When the engine 51 is stopped and the clutch 52 is disconnected, the electric vehicle 50 can perform EV travel using the drive motor 53. When the engine 51 is operated and the clutch 52 is connected, the electric vehicle 50 can perform parallel travel in which the output of the engine 51 is assisted by the drive motor 53. However, due to the one-motor system, drive and power generation using the drive motor 53 cannot be performed concurrently. Thus, there is a problem that the electric vehicle 50 cannot perform series travel or series parallel travel.
The “one-motor parallel system” provided with only one motor thus cannot perform series travel or series parallel travel. Therefore, the “one-motor parallel system” cannot satisfy users who request series travel or series parallel travel as well as cross-country performance.
Thus, existing systems cannot provide high cruising performance as EV while providing high cross-country performance as SUV. That is, existing systems cannot make the two performances compatible. In addition, when a drive motor or a power generation motor is added to an electric vehicle in order to obtain high cruising performance, it is necessary to take into consideration the influence of heat from an engine.